A phase-cut dimmer is included in an existing dimming system to phase-cut and then supply mains power to a load so that the load can be dimmed by the phase-cut dimmer phase-cutting the mains power. However dimming requirements are different and even significantly different among loads, e.g., lighting loads such as fluorescent lamp, so that a phase-cut power supply to the loads with different dimming requirements to dim the loads in the prior art may come with underutilization of the phase-cut power supply or insufficiency of the phase-cut power supply to dim the loads, and switching may render the loads dimmed inefficiently to thereby degrade the service life of the loads.